1. Field
The invention is related to event detection and mapping across the complete span of a fiber, and more particularly to measurement of the complete span distance of a fiber, measurement of complete loss across the span of the fiber, event detection and mapping across the complete span of a fiber and achieving trace showing the complete span of the fiber.
2. Related Art
The background information provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventor, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Long spans of fiber—on the order of 200 km—with splices every 5 km—made up of fiber with 0.3 dB/km loss and 0.1 dB per-splice loss drives the need for over 64 dB of dynamic range. To detect events on such a span—across the complete span—an optical time-domain reflectometer (OTDR) would require 70 dB of dynamic range. This is far beyond the capability of products in the field today.
In the current optical technology, no OTDR can shoot the complete span and measure the length of the fiber described above as it would require over 64 dB of dynamic range.
While high loss spans can be difficult to shoot, long spans in general are difficult to shoot for the same reasons as described above. While OTDRs can shoot 200 Kilometers (km) low loss spans, the event spacing/resolution can be poor due to the wide pulse widths required to do so. Accordingly, using shorter pulse widths on some long spans for better event location/resolution. Use of a 20 uS pulse width gives up to a 2 km location uncertainty as well as burying any events spaced closer than 2 km apart.
Therefore, there is a need for the ability to shoot a long fiber span for measurement of complete span distance, which cannot be simply estimated, measurement of complete loss across span, event detection and mapping across complete span and for acquiring a trace showing complete span of the fiber, so that the customer has confidence the fiber has not be tampered with or modified.